Although an electrical junction box incorporated in a vehicle has several structures such as an electrical junction box illustrated in FIGS. 4-5, there is a structure that has a difference of elevation in height at an edge of a frame (see Japanese Unexamined Patent Publication No. 2010-124562). Also, FIG. 4 is a cross sectional view indicating a conventional electrical junction box, and FIG. 5 is a perspective view indicating a part of a cover illustrated in FIG. 4.
An electrical junction box 301 illustrated in FIG. 4 provides a frame 302 that various components (not illustrated) such as a relay, a fuse, or the like are accommodated, and a cover 303 attached to the frame 302 and covering an opening portion 320 of the frame 302.
The frame 302 described above includes a peripheral wall 321 and the opening portion 320 that is surrounded by an edge 321a of the peripheral wall 321. As described above, there is a difference of elevation at the edge of the frame 302, namely the edge 321a of the peripheral wall 321, and the edge 321a includes a lower portion 304, a higher portion 306, an inclination portion 305 connected between the lower portion 304 and the higher portion 306. The lower portion 304 and the higher portion 306 extend to a vertical direction (arrow X or arrow Z) with respect to a mounting direction (arrow Y) of the cover 303. Also, the higher portion 300 is placed upper than the lower portion 304 in a state that mounts the electrical junction box 301 on a vehicle.
The cover 303 includes a ceiling wall 334, a peripheral wall 335 that is erected from an outer edge of the ceiling wall 334, and a double wall 333 that is provided to a lower end of the peripheral wall 335. The double wall 333 is formed of an exterior wall 331 and an interior wall 332, and the edge 321a of the peripheral wall 321 in the frame 302 is positioned between the exterior wall 331 and the interior wall 332. Also, as illustrated in FIG. 5, the edge 332a of the interior wall 332 includes a lower portion 314, a higher portion 316, and an inclination portion 315 that connects between the lower portion 314 and the higher portion 316. The lower portion 314, the inclination portion 315, and the higher portion 316 are respectively provided to a position of the lower portion 304, the inclination portion 305, and the higher portion 306 in the frame 302.
According to the electrical junction box 301 described above, in a state that the cover 303 is attached to the frame 302, a lapping amount between the peripheral wall 321 of the frame 302 and the interior wall 332 of the cover 303 is formed with a constant width over an entire periphery of the frame 302 and the cover 303. In other words, as illustrated in FIG. 4, a lapping amount “a” at the lower portions 304 and 314, a lapping amount “a” at the inclination portions 305 and 315, and a lapping amount “a” at the higher portions 306 and 316 are equal. Similarly, a lapping amount between the peripheral wall 321 of the frame 302 and the exterior wall 331 of the cover 303 are formed with a constant width over the entire periphery of the frame 302 and the cover 303.
In the conventional electrical junction box 301 described above, there is a problem that water easily enters from the neighborhood of the inclination portions 305 and 315 to the frame 302. For example, as illustrated with an arrow F in FIGS. 4-5, when strong water such as high pressure cleaning water splashes near the inclination portions 305 and 315, there is a problem that the water enters from the exterior wall 331 of the cover 303 and the peripheral wall 321 of the frame 302, flows to the higher portions 306 and 316, blows through between the interior wall 332 of the cover 303 and the peripheral wall 321 of the frame 302 into the frame 302, and splashes to the relay, the fuse, or the like.
Furthermore, when a packing is attached between the exterior wall 331 and the interior wall 332 of the cover 303, the problem of water entering described above is prevented. Meanwhile, when the packing is attached, a new problem that components costs and assembling costs are increased is generated.